Method of forming heads for boilers, pressure vessels, tanks, and the like



Aug. 16, 1955 H. H. GARY, JR

METHOD OF FORMING HEADS FOR BOILERS, PRESSURE VESSELS, TANKS, AND THELIKE Filed March 23, 1954 ,yarz refa H 2 HQ W ATTORNEY.

United States Patent Oflflce 2,715,377 Patented Aug. 16, 1955 NIETHOD OFFORD ENG HEADS FOR BOILERS, PRESSURE VESSELS, TAWKS, AND THE LIKEHartwell H. Gary, Jr., Norfolk, Va.

Application March 23, 1954, Serial No. 418,016

4 Claims. (Cl. 113-121) My invention relates to improvement in method offorming heads for boilers, pressure vessels, tanks, and the like, andmore particularly to a method of forming head closures which have acircular convexly curved head portion with an integral dependingcircumferential flange.

It is customary practice at present to form such circular convexlycurved head closures having an integral depending flange from flatsheets of steel, or other metal, by the use of dies, or by spinningoperations. The manufacturing cost of forming circular convexly curvedhead closures with an integral depending flange by spinning operationsis rather prohibitive. When only small quantities of such circularconvexly curved head closures of a certain diameter are required, thecost of the necessary dies and the cost of setting up the dies inpresses for the production of only a small quantity of heads is alsopractically prohibitive. In addition, such head closures when formed indies have certain inherent residual stresses set up in the metal, andsuch heads, preferably, after formation should be subjected to annealingprocesses to relieve the residual stresses.

One object of my invention is to provide a method by the use of whichcircular convexly curved head closures for boilers, tanks, etc. may beformed very economically in various desired diameter sizes without theincurring of the very substantial costs involved when dies and pressesare used to form such heads.

Another object of my invention is to provide a method by the use ofwhich residual stresses in the metal of which the head closure is formedare relieved contemporaneously with the forming of the convexly curvedportion of the head closure.

Another object of my invention is to provide a method by the use ofwhich the convexly curved portion of the head closure is formed bystretching of the metal itself, and without any shortening of thediameter of the head closure.

Another object of my invention is to provide a method by the use ofwhich the convexly curved portion will be formed simultaneously in twohead closures.

The accompanying drawings show somewhat diagrammatically the progressivesteps in my improved method, which has proven to be very satisfactory incommercial use.

In said drawings, Fig. 1 is a somewhat diagrammatic sectional view oftwo separated plane head closures provided with integral circumferentialflanges.

Fig. 2 is a sectional view similar to Fig. l and with the opposedflanges of the heads in engagement with each other and a circularsupport ring interposed between the two head closures.

Fig. 3 is a somewhat diagrammatic elevation of the structure shown inFig. 2, and with the two head closures welded together circumferentiallyat the point of contact of their respective flanges.

Fig. 4 is a top plan of the structure shown in Fig. 3.

Fig. 5 is a side elevation of the structure shown in ill) Fig. 3 andwith the plane surfaces of the heads expanded to convexly curvedconfiguration by internally applied fluid pressure.

Fig. 6 is an elevation of the structure shown in Fig. 5 and with the twohead closures shown cut apart at the weld which connected the respectiveflanges together, and with the support ring removed.

Fig. 7 is an elevation of a convexly curved head closure made with theuse of my improved method.

Referring to said drawings, Fig. 1 shows somewhat diagrammatically twocircular head closures 1 formed from flat sheet steel, or other metal,and which are provided with integral depending flanges 2 which areformed by any of the methods well known in the art. Of course, saidflanges 2 may be formed by welding a circumferential depending strip ofthe proper Width to the plane head portion 3 of the head closure.

One of the pair of head closures 1 is provided with an axial opening inwhich a fluid conduit means 5 is mounted in fluid tight relationshipwith the plane head portion 3. The fluid conduit means 5 is connectedwith a fluid conduit 5a which is connected to a convenient source offluid under pressure sufficient to bulge the plane head portion 3 toconvex configuration, as hereinafter described.

As shown in Fig. 2, a circular metal ring 6 of substantially the samediameter as the internal diameter of the flange 2 is inserted betweenthe two head closures 1. The ring member 6 is, conveniently, of generalblock 0 shape in cross section, and is of sufiicient section towithstand, without deformation, the radial stresses resultant from theintroduction of fluid under pressure to tween the heads, the radialstresses of the fluid pressure would cause extreme buckling of the headsand the flanges.

As shown in Fig. 2, the width of the ring member 6 is slightly less thanthe distance between the inside surfaces of the two plane head portions3 when the flanges 2 thereof are positioned together, as indicated inFig. 2.

As shown in Fig. 3, the two heads 1 are welded togethercircumferentially at the abutting portions of their flanges 2, asindicated at 7. Fluid under pressure is then introduced into the twowelded together head closures through the fluid conduit means 5 from thesource of fluid under desired pressure. The member 6 being of ring form,the forces of the fluid under pressure will be exerted uniformly on theinside faces of both plane head portions 3, and will cause the planesurfaces 3 of each head closure to be bulged uniformly from a plane formas shown at 3 in Figs. 1, 2 and 3 to the convexly curved configuration9, as shown in Figs. 5, 6 and 7.

Fluid pressure applied through the fluid conduit means 5 will cause theplane surfaces 3 to bulge in an even or uniform manner, and the fluidpressure is increased in value until the head portions have bulged tothe required radius of dish. When the head portions have been bulged tothe desired radius, the fluid pressure is relieved from 2 circularconvexly curved head closures of the desired 3 radius of dish and withintegral depending flanges of the desired diameter.

The head closures may then be inserted in the opposite ends of thepreformed cylindrical body portion of the boiler, pressure vessel, tank,and the like, and the heads integrally connected with the body portionof the boiler, etc., in any well known manner, such as by welding.

It is obvious that various modifications may be made in my improvedmethod without departing from the essential features thereof, and, I donot desire to limit myself to the precise details of the method asherein described.

I claim:

1. The method of making head closures for boilers, pressure vessels,tanks, and the like consisting in forming circular head closures with aplane head portion and a depending circumferential flange from flatsheet metal; providing a plane head portion with axial fluid conduitmeans in communication at its inner portion with the interior of saidhead closure and adapted to be connected at its outer portion to asource of fluid under pressure; positioning two of said head closurestogether, one of which being provided" with a said fluid conduit means,in axial alignment and with their respective circumferential flanges inabutting relationship and with a circular metal'ring member, havingsubstantially the same outside diameter as the internal diameter of saidflanges, positioned within said pair of head closures, with said ringmember in substantially fluid-tight circumferential contact with therespective flanges of each head closure near the junction of the flangeand plane head portion; circumferentially welding the flanges of saidhead closures together at their abutting surfaces; subjecting the planehead portions of said two welded together head closures to internalpressure by means of fluid under pressure introduced through said fluidconduit means, said fluid under pressure being of a value suflicient tobulge convexly the plane head portions of said welded together headclosures to the desired radius of dish; relieving said internal fluidpressure when said head portions have been 'bulged convexly to thedesired radius of dish; cutting the two head closures apart at theirside flange portions; and removing said ring member from within saidhead closures.

V 2. The method of making head closures for boilers, pressure vessels,tanks, and the like consisting in forming circular head closures with aplane head portion and a depending circumferential flange from flatsheet metal;

providing a plane head portion with fluid conduit means in comunicationat its inner portion with the interior of said head closure and adaptedto be connected at its outer portion to a source of fluid underpressure; positioning two of said head closures together, one of whichbeing 7 provided with a said fluid conduit means, in axial alignment andwith their respective circumferential flanges in abutting relationshipand with a circular metal ring member, of general channel cross sectionand having substantially the same outside diameter as the internaldiameter of said flanges, positioned within said pair of head closures,with the flange portions of said channel shaped ring member insubstantially fluid-tight circumferential contact with the respectiveflanges of each head closure near the junction of their flange and planehead portion; circumferentially welding the flanges of said headclosures together at their abutting surfaces; subjecting the plane headportions of said two welded together head closures to internal pressureby means of fluid under pressure introduced through said fluid conduitmeans, said fluid under pressure being of a value suificient to bulgeconvexly the plane head portions of said welded together head closuresto the desired radius of dish; relieving said internal fluid pressurewhen said head portions have been bulged conveXly to the desired radiusof dish; cutting the two head closures apart at their side flangeportions; and removing said ring member from within 7 said headclosures.

3. The method of making head closures for boilers, pressure vessels,tanks, and the like consisting in forming circular head closures with aplane head portion and a depending circumferential flange from flatmetal; providing a plane head portion with fluid conduit means incommunication at its inner portion with the interior of said headclosure and adapted to be connected at its outer portion to a source offluid under pressure; positioning two of said head closures together,one of which being provided with a said fluid conduit means, in axialalignment and with their respective circumferential flanges in abut tingrelationship and with a circular metal ring member, of general block 6configuration in cross section and hav ing substantially the sameoutside diameter as the internal diameter of said flanges, positionedwithin said pair of head closures, with said block 0 shaped ring memberin substantially fluid-tight circumferential contact with the respectiveflanges of each head closure near the junction of their flange and planehead portion; circumferentially welding the flanges of said headclosures together at their abutting surfaces; subjecting the plane headportions of said two welded together head closures to internal pressureby means of fluid under pressure introduced through said fluid conduitmeans, said fluid under pressure being of a value suflicient to convexlybulge the plane head portions of said welded together head closures tothe desired radius of dish; relieving said internal fluid pressure whensaid head portions have been bulged conveXly to the desired radius ofdish; cutting the two head closures apart at their side flange portions;and removing said ring member from within said head closures.

4. The method of making head closures for boilers, pressure vessels,tanks, and the like consisting in forming circular head closures with aplane head portion and a depending circumferential flange from flatmetal; provid ing a plane head portion with fluid conduit means incornmunication at its inner portion with the interior of said headclosure and adapted to be connected at its outer portion to a source offluid under pressure; positioning two of said head closures together,one of which being provided with a said fluid conduit means, in axialalignment and with their respective circumferential flanges in abuttingrelationship and with a circular metal ring member, provided with anintermediate circumferential recess portion and having substantially thesame outside diameter as the internal diameter of said flanges,positioned within said pair of head closures, with said ring member insubstantially fluid-tight circumferential contact with the respectiveflanges of each head closure near the junction of their flange and planehead portion; circumferentially welding the flanges of said headclosures together at their abutting surfaces; subjecting the plane headportions of said two Welded together head closures to internal pressureby means of fluid under pressure introduced through said fluid conduitmeans, said fluid under pressure being of a value sufiicient to convexlybulge the plane head portions of said welded together head closures tothe desired radius of dish; relieving said internal fluid pressure whensaid head portions' have been bulged convexly to the desired radius ofdish; cutting the two head closures apart at their side flange portions;and removing said ring member from within said head closures; whereby,the residual stresses in the metal of which said head closure is formedare relieved contemporaneously with the forming of the convexly curvedportion of said head closure.

References Cited in the file of this patent UNITED STATES PATENTS2,503,190 Branson Apr. 4, 1950 FOREIGN PATENTS 115,957 Australia Q Sept.29, 1942

